Opposed piston engine



May 1936.V F 1V MULUGAN n 2,049,182

OPPOSED PISTN ENGINE 4 Filed Dec. 20, 1932 2 Sheets-Sheet l IN VENT OR 'Pggl CMUZZZ'QJIZ A lORA/EY ay l2, 1936. P. c. MULLIGAN OPPOSED PISTON ENGINE Filed Deo. 2'0, 1932 2 Sheets-Sheet 2 INVENTOR Z .Muilzgfm Patented May 12v, 1936 UNITED STATES PATENT OFFICE y 2,040,182 OPPOSED PISTON ENGINE Application December 20, 1932, Serial No.` 648,065

12 Claims.

My invention .relates to"4 engines generally, and embodies certainprinciples which can be employedirr fluid pressure engines, of whicha steam enginemay be taken: as typical.

The ordinary types o-f reciprocating fluid pressure wherein the cylinder is mounted upon or formedintegral with a-crankcase into which itlopens; and in which a single-piston is reciprocaole because` of pressures permitted to expand "between the piston and a fixed cylinder head, are open to numerous' objections.

It is myobject to:` devise an engine having certain advantages, as will appear hereafter-` For example, it "provides a convenient andextremely simple means 'to control' the admission of fresh steam, and` the exhaust of spent steam. It provides aY simple and-` light construction, wherein thecrankcase may be accessible at all'times, even while `the engine is running.

It is alsoan object to devise a construction wherein any cylinder, with its pistons, can be quickly and4 easily removed from` replaced upon theengine, Without disturbing the remainder of the engine, without draining the crankcase, etc.

A further obj ect isfoundin the complete separation of the `crankcase from the expansion chamber.

A furtheriobject lies in the provision of a simple means for controlling, particularly for closing, the inlet valve'in such an engine.

With these and other objects in mind, as. will appear inthisspecication, my inventioncomprises the .novelparts and thenovelcombinations and' arrangements thereof, as shown in the accompanyingl drawings,.desc1ibed in this specification, and .as will be more particularly pointed out by. the claimswhich .terminate the same.

Inthe accompanying drawingsllhave shown my invention embodiedin an..` illustrative. form, as a steameng-ine. i

Figure-1 is a vertical-sectionalview through a steam engine embodying my invention.`

Figure 2` is-a transverse. vertical sectional view, in part onthe crank shaft, and infpart along the cam.l shaft, ofl theengine. i

The principles of operation indicated above having thefadvantages enumerated, and-others, can be incorporated-in engines generally designated as fluid.- pressure engines, of which' the steam engine-shown in Figures l and 2 is an eX- ample. Tliedescription of a steamengineis not intended to exclude, but rather to include, other fluid-pressureengines, `which latterr'are. to be un'- derstood when the steam engine,v representative of this type, is referred to herein.

A horizontal cylinder I is provided with! two opposed pistons 2 andzZ, asV shown ini` Figure. 1. These pistons are connected to the crank shaft 3, mounted below and at right angles to the axis of the cylinder, through rocker beams 4 and 4', respectively, each on a rocker shaft 40 held in bearings 45'in the frame.` Theupper end of each rocker beam is connected to its piston by a pitman 20, and the lower end is connected to the crank shaft by a simlarpitman.

The main frame may be Yformedof two or more plates 5, held rigid and spaced apart by suitable spacers 59, these plates supporting the discharge manifolds l2, and the cylinder in turn supported from thedischarge manifolds. The roc-ker arm and associated parts may be housed within a cover 54 To remove the cylinder andvalve hereafter to be described, it is only necessary to remove the cover 54', the straps 58 holding down the dischargeV manifolds, and to disconnect the pitman 28 from-the rocker beam, and, of course, the supply and discharge manifolds from their connections to other cylinders, or to piping.

Steam is supplied through a manifold 8, and a valve is controlled while opening, through a stem 82 carrying a cam follower 83, by means of a suitable cam 84 mounted upon a cam shaft 85. The cam shaft', journaled in the frame, is suitably timed from the crank shaft 3, as for example by the gears indicated at 86. Since the speed of the steam engine is controlled by the time and duration ofV admission, the cam shaft 85 is mounted to be movable axially, and the cams 84 are made .in sections which are varied with relation to adjoining sections. Axial movement of the cam shaft is suitably controlled, as for example by the control handle 8l connected to its end (see Figure 2), and this movement brings the different sections of the` cam into engagement, selectively, withvthe cam follower, thus to control the valve 80.

The valve 80 is seated above the cylinder l, and the stem 82 extends completely through the cylinder. At its-lower end a. head 88. is received and packed in a recess 89 open to the interior of the cylinder l, and vented to the discharge manifold' l2 below the head 88. Pressure Within the cylinder, acting upon this head'will close the valve without the necessity of employing any spring means or other positive means to close it, yet the excess of pressure on the head, over that effective on the valve. itself, isnot so great that 55 the valve will not readily open when raised by the cam 84.

This construction has the advantages of being easily and cheaply machined, assembled and maintained in best working condition, and also it permits the use of steam at high pressures and superheated temperatures, without the necessity and usual difficulty of valve-rod packing, the sealing of the valve-rod being accomplished by means of the small piston and rings mounted thereon, the valve-rod packing, below the rod-Y piston chamber, having only to resist and seal the relatively low pressure of the exhaust steam in the exhaust manifold. Y

The cylinder being in eect free from connections tol the frame, and under no1 longitudinal stresses, high pressures and temperatures will produce only radial stresses equalized throughout. Accordingly undue torsional and expansion stresses and strains cannot develop.

What I claim as my invention is:

1. In` combination, a cylinder, a pair of oppositely movable pistons therein,` a crank shaft below vand at right angles to the cylinders axis, means operatively connecting the pistons with the crank shaft, a cam'shaft driven from and parallel to the crank shaft, and located between the latter and the cylinder, a variable cam on said cam shaft, a cam follower fixed relative to the cylinder and disposed for engagement by said cam, means to shift the cam shaft axially, thereby to control the movement of said cam follower by engagement thereof by a different portion of the cam, the cylinder having a steam inlet port in its top, admitting to the point of closest approach of the pistons, a poppet valve controlling said inlet port, and having its stem extending through the space within the cylinder and projecting therebelow to support said cam follower, and a piston secured upon the Vvalve stem below the lowest level of the cylinder, the cylinder having a pocket within whichis sealed said latter piston, thereby by steam pressure to effect closing of the valve, said pocket below the piston having a vent. l

2. In a fluid pressure engine, in combination with a pressure. chamber, an inlet valve cooperating withV a seat at one side of said chamber,

the valve stem extending across the chamber, a balance head secured upon said stem upon the side opposite the valve and seat, one face of said head being in free communication with pressures within the chamber, and the other face being under reduced pressure, whereby the internal pressures constitute the sole agency to move the valve to its seat, and positive means to open the valve.

3. In a fluid pressure engine, in combination with a pressure chamber, an inlet valve cooperating with a seat at one side of said chamber, the stem of said valve extending across the chamber and through its opposite wall, external means engageable with the projecting stem to raise the valve from its seat, the chamber wall having a pocket surrounding the valve stem, the lower end of which pocket is vented, and a balance head upon said valve stem sealed and slidable in said pocket, its upper end being exposed to the pressures' within the chamber, whereby the valve is moved to its seat by such pressures.

4. In a iiuid pressure engine, in combination, a cylinder freely open vat each end, two pistons oppositely reciprocable therein to define a fluidpressure chamber between them, a shaft, operative connections Vbetween each piston and said shaft to rotate the latter, exhaust ports at an end of the cylinder located to be uncovered by the corresponding piston as it reaches the outer limit of its stroke, an inlet port communicating with the space between the pistons at the inward limits of their strokes, a poppet valve controlling the admission of the fluid pressure medium through said inlet port, the stem of said valve extending through the expansion chamber and having a piston member thereon, and a valve piston chamber having one end in communication with the fluid-pressure chamber and receiving said piston, thereby to tend to move the valve towards its closed position.

5. The combination of claim 4, wherein an exhaust conduit is provided for the pressure medium discharged from the exhaust ports, and a conduit connects the end of the valve piston chamber, opposite that which is in communication with the fluid-pressure chamber, with said exhaust conduit. 6. In combination, a horizontal cylinder, a crankshaft disposed normal to and centrally beneath said cylinder, a cam shaft beneath said cylinder disposed parallel to and vertically above said crank shaft and driven therefrom, a valve admitting directly into said cylinder, a valve stem extending through said cylinder wall and projecting radially downward therefrom for actuation by said cam shaft, two opposed pistons in said cylinder, and means interconnectingsaid pistons and said crankshaft.

7. In combination, two spaced upright plates defining a frame, a, horizontal cylinder disposed therebetween and removably supported therefrom, a crankshaft journaled in said plates normal to and centrally beneath said cylinder, a cam shaft journaled in said plates beneath said cylinder and parallel to and vertically above said crank shaft and driven therefrom, a valve admitting directly into said cylinder, a valve stem extending diametrically through said cylinder and projecting radially downward therefrom for actuation by said cam shaft, two opposed pistons in said cylinder, and means interconnecting said pistons and said crankshaft.

8. Valve mechanism for controlling the admission of fiuid from a supply source to a uidpressure chamber, comprising a seat in said chamber, a valve therefor, and means for moving said valve, said means. being movable towards Valve-closed position solely under the influence of pressure communicated thereto from said fluid-pressure chamber.

9. Valve mechanism for controlling the admission of uid from a supply source to a uid-pressure chamber, comprising a seat in said chamber, a valve therefor, a piston member operatively connected to said valve, and a valve-piston chamber receiving said piston member and communieating with said fluid-pressure chamber for moving the piston member by pressure received therefrom, to move said valve to its seat.

10. Valve mechanism for controlling the admission of fluid from a supply source to a uidpressure chamber, comprising a valve seat in one side of said chamber, a valve therefor, a valve stem extending across such chamber, a piston member on said valve stem, and a valve-piston chamber at the opposite side of said fluid-pressure chamber receiving said piston member, and having one end opening into the fluid-pressure chamber for moving the piston member by pressure received therefrom to move said valve to its seat.

11. Valve mechanism for controlling the admission of fluid from a supply source to a fluidpressure chamber, comprising a seat in said chamber, a valve therefor, a valve-operating cam, and a piston member operatively connected to said valve and actuated by the pressure in said fluid-pressure chamber, and constituting the sole means to maintain said valve in position for operation by said valve-operating cam.

12. In combination, a cylinder, a pair of oppositely movable pistons therein, a crank shaft, means operatively connecting said pistons with said crank shaft, said cylinder having a steam inlet port in one side admitting to the point of nearest approach of the pistons, a steam inlet valve controlling said port and having a stern extending through the cylinder, means timed with the crank shaft, to engage said stem and to op'en said valve at intervals, and means on said stem, on the side of the cylinder opposite to said valve, and responsive to pressure Within the cylinder to move and hold the valve to its seat, during inaction of the preceding means.

PAUL C. MULLIGAN. 

